Hello, I saw that the bug was fixed and tried the kernel, but it seems I did a bad diagnostic. As found in https://bugs.archlinux.org/task/55024, it seems that the required options for backlight control to work out-of-the-box in Cherry Trail tablets are:
CONFIG_PWM=y CONFIG_PWM_SYSFS=y CONFIG_PWM_CRC=y CONFIG_PWM_LPSS=m CONFIG_PWM_LPSS_PCI=m CONFIG_PWM_LPSS_PLATFORM=m I apologize for the earlier misleading report... Pablo B.
